Abrasive disc and holder therefor



June 24, 1958 M. ElSENBElS ABRASIVE DISC AND HOLDER THEREFOR Filed Oct. 1, 1956 15 2117 25 Jzz dez? 502" I waif/Zea g zj'erzezfi OZ ii'a r27 69 United StatesPatent ABRASIVE DISC AND HOLDER THEREFOR Matthew Eisenbeis, Des Plaines, Ill.

Application October 1, 1956, Serial No. 613,322

12 Claims. (Cl. 51-495) This invention relates to an abrasive disc and holder therefor, and more particularly to a combination of this type especially directed to an improved means for releasably securing the abrasive disc to the disc holder.

In grinding or abrading structures wherein an abrasive disc is releasably carried by a disc holder and is rotatably driven thereby, an ever-present problem is that of providing a mounting means for the disc on the holder which affords quick and easy securance and release of the abrasive disc, while providing a positive lock therefor-securely anchoring it to the disc holder when in place thereon. Various types of fastening devices have been conceived with the intention of accomplishing such results, but none of these have been satisfactory. Several of these known fastener arrangements are unsuitable, for upon initiation of the rotary movement the inertia of the abrasive disc results in relative movement between it and the disc holder, whereby there is a loosening of the disc on the holder. In other arrangements, an opposite result occurs in that centrifugal force tends to cause the disc to spin off when rotation of. the disc holder is terminated.

In certain of the prior art devices, the fastening or mounting means is of such character that there is a serioustendency for the abrasive disc, and more particularly the stiff backing material thereof, to tear whereupon the abrasive disc unit must be replaced even though the abrasive face thereof is not worn. Another apparent disadvantage in certain structures now in use is that they are not quickly and easily secured and released from the disc holder with the result that mounting and replacement is a tedious and time-consuming task.

It is, accordingly, an object of the invention to provide an abrasive disc and holder therefor which overcome a number of serious disadvantages present in prior art structures of this character. Still another object of the invention is that of providing a structure of the character described wherein an abrasive disc unit (the unit comprising the abrasive disc per se and the backing member thereof to which it is ordinarily adhesively secured) can be mounted upon and removed from the disc holder therefor in a simple operation requiring only a slight twisting or rotational movement therebetween, taking but a modicum of time.

Yet another object is to provide an improved arrangement of the type described wherein the abrasive disc unit is held under tension by a firm, positive locking device that prevents spin-off of the disc through the effects of centrifugal force when rotation is terminated, but .also prevents loosening of the disc unit due to inertia when rotation is started, and that avoids tearing of the backing member for the abrasive disc. provisionof a positive locking arrangement for securing the abrasive disc unit to the holder therefor that comprises a plurality of circumferentially spaced tongues or looking prongs that are extensible through slots provided therefor in the abrasive disc unit-the prongs being adjustable for selectively establishing the gripping action A further object is in the v 2,839,879 Patented June 24, 1958 disc unit and holder therefor shown in operational 'position with respect to'a hand drill that in this illustration provides the rotational driving means; Figure 2 is an end.

view in elevation of the abrasive disc unit and holder therefor taken on the line 22 of Figure 1, and with the central area of the abrasive disc broken away; Figure 3 is an end view in elevation of the device taken from the opposite direction of that of Figure 2 and along the line 3-3 of Figure 1; Figure 4 is an enlarged broken transverse sectional view taken along the line 4- --4 of Figure 2; and Figure 5 is an enlarged broken sectional view taken along the are 55 of Figure 2.

The abrasive disc and holder device illustrated in its entirety in Figure l is designated with the numeral 10.,

This device comprises the abrasive disc unit 11 and the disc holder 12, and it is seen to be mounted upon an electric power drill 13 that, as is well known, has an electric motor equipped with a chuck 14 in an arrange.

ment whereby the motor rotates the chuck. Any other suitable device may be used for'imparting rotation to the assembly 10, and to some extent the particular powerdevice employed will depend upon the size of the abrasive disc assembly. It should be apparent that the abrasive disc unit 11 and its holder 12 may be made in various sizes, and itis contemplated that a number of different sizes will be made commercially available.

The abrasive disc unit ll comprises an abrasive disc. 15 and a backing member 16 to which it is ordinarily ad hesively secured. The outer face of the abrasive disc- 15 will be provided with abrasive particulate matter so that upon rotation thereof, it may be used for grinding or abrading a surface that is brought into engagement therewith. The backing member 16 may be formedof any suitable material, and ordinarily will be a relatively tion 17 of the backing member, it will be seen that the bottom wall 19 is provided with a plurality of circumferentially spaced apart slots or openings 20there being three in number in the illustration given, and these are equally, spaced apart.

gripper prongs 21 that are struck from the bottom wall 2 of a mounting disc or adapter 23 provided by the disc holder 12. I

The disc holder also comprises a backing disc or driver 24 and a stem or drive shaft 25. The drive shaft 25 Y is adapted to be received-within the chuck 14 of the drill 13, as is shown in Figure 1, and the driver 24 and adapter 23 are centrally apertured so as 'to receive a reduced end portion of the shaft 25. adapter will be secured to the shaft so as to be rotatably driven thereby, and such securance may comprise a press fit, or other comparable securing means may be employed. If desired, the reduced end of the shaft 25 may be .swaged outwardly to form aflange or collar 26 that presses the driver and adapter tightly against the The slots 20 are adapted tohave inserted therethrough the respective locking tongues or' The driver and s holder and facilitate mounting the same thereon. It is I also apparent from Figure 4 that the adapter'or mount-:

ing member 23' is dished inwardly throughout its central portion so as to conform in configuration with the central dished portion 17 of the abrasive disc unit. illustrates best that the tongues or prongs 21 each have an outwardly turned tip 29 that facilitates the insertion of the prongs into and through the slots 2% for the backing member 16. The prongs 21 are arcuate and the longitudinal axis thereof lies along the circumference of a circle subscribed using the longitudinal axis of the shaft 25 as the center thereof.

It should also'be noted in Figure 5 that the tongues 21 are integral with the adapter 23 and are struck from the bottom wall 22 thereof. This leaves a plurality of openings in the bottom wall each corresponding to the size and shape of the tongue. it has been found that if such openings are left in the adapter, there is a tendency for the bottom wall 19 of the backing member 16 of the abrasive disc unit to tear in the areas of the slots 20 during use. This tendency totear can be overcome by providing the backing disc 24 and striking therefrom or embossing the same in alignment with the openings 30 in the adapter, backing or filler tongues 31 that correspond substantially to' the size and shape of the openings 30 and thereby fill the same. These filler tongues 31 then tend to form a continuation of the bottom wall 22 of the adapter so that it provides in effect a unitary planar surface engaging the bottom wall 19 of the abrasive disc backing member.

"Ihe backing disc 24 and adapter 23 may be formed of metal, and the prongs 21 thereof are bendable along their integral connections with the bottom wall of the adapter. Thus, the. prongs can be adjusted-that is, moved toward or away from the planar surface of the bottom wall 22 so as to increase and diminish, respectively, the gripping force exerted thereby on the bottom wall 19 of the abrasive disc backing member.

To mount the abrasive disc unit 11 on the disc holder 12,it is only necessary to move these two devices toward each other, and the inclined wall lb ofthe abrasive disc backing member and the correspondingly inclined wall 32 of the adapter together with the end 28 of the shaft which serves as a centering pin, positively align and posiabrasive disc unit 11 from the holder is accomplished by reversing the twisting or relative rotational movement between the two members.

When in position on the disc holder, the tongues 21 press against the end wall 19 of the abrasive disc backing member 16, and that bottom wall in turn presses against the filler tongues 31 provided by the backing disc 24 and which form a continuation of the adapter bottom wall 22. Thus, the member 16 is held under tension and because of'the filler tongues 31, there is no. tendency y for the backingfmember to tear. The orientation of the parts and interrelation therebetween prevent loosening of the abrasive disc unit upon starting rotation of the holder. .12, and spin-01f at the termination of the rotational movement is also prevented. The prongs 21 are bend- Figure 5 able, whereby the gripping action thereof against the backing member 16 is readily adjusted.

While in the foregoing specification an embodiment of the invention has been disclosed in considerable detail for purposes of making the same clear, it will be apparent to those skilled in the art that numerous changes and additions may be made to those details without departing from the spirit and principles of the invention.

I claim:

1. In a disc holder of the character described, a mounting disc provided with a plurality of gripper tongues struck therefrom, a backing disc in contiguous relation with said mounting disc along the side thereof remote from ,said outwardly struck gripper tongues, said backing disc providing a plurality of filler tongues one for each of said gripper tongues and filling the spaces left thereby when struck from the mounting disc, and a shaft secured to said mounting and backing discs for rotatably driving the same.

2. The disc holder of claim 1 in which'said gripper tongues are spaced apart along a circumferential arc subscribed about the rotational axis of said shaft,'and in which said gripper tongues are arcuate and have outwardly turned ends.

3. In an abrasive disc holder of the character described, a drive shaft adapted to be rotatably driven, a backing disc secured to said shaft, and a mounting disc also secured to said shaft, said mounting disc being centrally dish-shaped andthe bottom wall thereof being in contiguous relation with said backing disc, said bottom wall.

being struck outwardly at arcuatcly spaced apart points therealong to form gripper tongues, said backing plate being pressed outwardly at spaced apart points aligned with said gripper tongues to form filler tongues for the spaces left in said bottom wall when said gripper tongues are struck therefrom, whereby said bottom wall provides a substantially uninterrupted planar surface.

4. The apparatus of claim 3 in which each of said tongues is provided with an outwardly turned end and has an arcuate longitudinal axis.

5. The disc holder of claim 3 in which each of said gripper tongues is bendable for selectively adjusting the gripping force exerted thereby upon a member interposed between the tongues and saidzbottom wall.

6. In combination, a mounting disc provided with a plurality of gripper tongues struck therefrom, a backing disc in contiguous relation with said mounting disc along the side thereof remote from said outwardly struck grippertongues, said backing disc providing a plurality of filler tongues one for each of said gripper tongues and being positioned in the spaces left thereby when the gripper tongues are struckfrom the mounting disc, a shaft secured to said mounting and backing discs for rotatably driving the same, an abrasive disc, and a backing member secured thereto, said backing member being formed of a relatively stiff material and having a plurality of spaced apart slots alignable with the respective gripper tongues and receiving the same therein.

7. In a structure of the character described, a shaft adapted to be rotatably driven, a backing disc secured to said shaft and having a plurality of outwardly projecting filler tongues pressed therefrom, said filler tongues being spaced apart circumfercntially about the rotational axis of said shaft, a mounting disc having a central dished portion providing a bottom wall secured to said shaft and lying in facing planar relation with said backing disc, said bottom wall having a plurality of gripper tongues struck outwardly therefrom and providing openings therein, there beingone gripper tongue and opening for each of said filler tongues, said gripper tongues and openings being aligned with the filler tongues positioned within said openings to form in effect a continuation of said bottom wall, a backing member centrally dished and conforming dimensionally to the centrally dished portion of said mounting disc, said backing member having a slot therein for each of said gripper tongues and receiving the gripper tongues therein for mounting the backing member on said mounting disc, and an abrasive disc secured to said backing member.

8. The device of claim 7 in which said backing member is centrally apertured, and in which said shaft is provided with a reduced extension forming a centering pin received within said aperture.

9. The device of claim 7 in which said gripper tongues are adjustably bendable to select the gripping force exerted thereby on said backing member.

10. In a disc holder of the character described, a mounting disc provided with a plurality of gripper tongues struck outwardly therefrom, a backing disc adjacent said mounting disc along the side thereof remote from said outwardly struck gripper tongues, said backing disc being equipped with a plurality of filler tongues one for each of said gripper tongues and substantially filling the spaces 6 left thereby when struck from the mounting disc, and means for rotatably driving said mounting and backing discs.

11. The disc holder of claim 10 in which said filler tongues are integral with said backing disc and comprise depressed portions thereof.

12. The disc holder of claim 11 in which means are provided for clamping said backing disc to said mounting disc to constrain said filler tongues in the spaces of said 1 mounting disc.

References Cited in the file of this patent UNITED STATES PATENTS 368,457 Clark Aug. 16, 1887 2,597,102 Jensen May 20, 1952 2,747,343 Gellert May 29, 1956 

